The present invention relates to a method of detecting a position of a printing medium which is performed in a printing apparatus.
In recent years, printers are commercially distributed to enable printing information such as texts, images, etc. on a labeled surface of an optical recording medium, for example, CD-R (Compact Disk Recordable), etc. In the case where such printer is used to print on an optical recording medium in the form of a disk, a disk tray is in some cases used to hold the optical recording medium to feed the same into the printer.
Such disk tray comprises a part for supporting an optical recording medium, and the disk tray moves in a secondary scanning direction (a direction of conveyance of a printing medium such as paper) of the printer to enable a recording head to print on a labeled surface of an optical recording medium.
By the way, in case of printing on such optical recording medium, correct printing cannot be performed unless the printer recognizes a size and a position of the optical recording medium. Hereupon, Japanese Patent Publication No. 2004-114357A discloses a method of using a printer to print scales on an adjustment medium having the same shape of CD-R, on which a reference line is beforehand printed, identifying shift of a printed position according to how the reference line and the scales overlap, and adjusting a printed position according to the identified shift.
Alternatively, there is proposed a method of applying a marker in a predetermined position on a disk tray, reading the marker with an optical sensor, indirectly finding a position of an optical recording medium from the positional relationship between the marker and a support part for the optical recording medium, and adjusting a printed position according to the position as found.
By the way, with the former technique disclosed in Japanese Patent Publication No. 2004-114357A, it is necessary to print scales on an adjustment medium in order to perform the positional adjustment, and it is also necessary for a user to visually confirm results of printing, thus causing a problem that an operation is complicated.
Also, with the latter technique, a marker provided on a disk tray is sometimes varied in light optical reflectance due to secular change, in which case there is caused a problem that it is not possible to correctly detect a position of a marker.